A 25-year-old woman, gravida 3 para 0 aborta 2, at 6 weeks gestation comes to the office for a routine prenatal visit. The patient says she feels fine except for mild nausea; she takes no medications other than a prenatal vitamin. Her 2 prior pregnancies ended in first-trimester spontaneous abortions. Prior to this pregnancy, the patient drank alcohol on social occasions, and she does not use tobacco or illicit drugs. She is in a monogamous relationship and has never been diagnosed with or treated for a sexually transmitted infection. Laboratory results are as follows:
| Complete blood count | |
| Hematocrit | 33% |
| Platelets | 98,000/mm3 |
| Leukocytes | 7,000/mm3 |
| Coagulation studies | |
| Prothrombin time | 10 sec |
| Activated partial thromboplastin time | 46 sec |
| VDRL | positive |
| FTA-ABS | negative |
Urinalysis shows no blood or protein. Sonogram shows a 6-week fetal pole with cardiac motion. Which of the following is the best next step in the management of this patient?
Diagnostic criteria for antiphospholipid-antibody syndrome (1 clinical & 1 laboratory criterion must be met) | |
Clinical | Vascular thrombosis
Pregnancy morbidity
|
Laboratory |
|
This patient with abnormal serologic test results (eg, positive VDRL, prolonged activated PTT) and 2 prior spontaneous abortions most likely has antiphospholipid-antibody syndrome (APS), a prothrombotic autoimmune disorder caused by antiphospholipid antibodies (eg, anticardiolipin antibody, lupus anticoagulant). These antibodies can cross-react with a VDRL test to produce a false-positive result; they can also interfere with coagulation test reagents, resulting in an artificially prolonged activated PTT. Mild thrombocytopenia (immune mediated) is typical.
Antiphospholipid antibodies disrupt the function of platelets and vascular endothelial cells to create a hypercoagulable state. For this reason, the initial presentation of APS is often an unprovoked arterial or venous thrombosis (eg, stroke, deep venous thrombosis). In pregnant patients with APS, persistent thrombosis of placental vessels causes pregnancy complications or recurrent pregnancy losses, as in this patient.
Although additional antibody testing is needed to confirm the diagnosis of APS in this patient, the best next step is to initiate anticoagulation to decrease her risk of thrombosis and pregnancy complications. In pregnant patients, the anticoagulant typically used is low-molecular-weight heparin, which is not associated with teratogenicity.
(Choices A and B) Benzathine penicillin is used to treat syphilis, which is classically diagnosed when a screening test (eg, VDRL, a nontreponemal test) and a subsequent confirmatory test (eg, fluorescent treponemal antibody absorption [FTA-ABS], a treponemal test) are both positive. This patient's VDRL is likely a false-positive given her APS, and confirmatory testing with FTA-ABS (more specific than nontreponemal testing) is negative, making syphilis unlikely. Azithromycin is used to treat chlamydia, which is also unlikely in this low-risk patient (ie, age >24, no prior sexually transmitted infections).
(Choice D) Corticosteroids (eg, prednisone) can be used to treat systemic lupus erythematosus (SLE), which is often associated with APS due to shared antibodies (eg, lupus anticoagulant). Although SLE can cause spontaneous abortion and thrombocytopenia, patients typically have additional renal and rheumatic disease (eg, lupus nephritis, arthritis). This patient's urinalysis shows no blood or protein, making SLE less likely. Corticosteroids are not used to treat APS.
(Choice E) Warfarin is an anticoagulant commonly used for long-term management of APS; however, it is contraindicated in pregnancy due to teratogenicity. After delivery, this patient may be transitioned to warfarin.
Educational objective:
Antiphospholipid-antibody syndrome (APS) is a prothrombotic autoimmune disorder that can present with recurrent pregnancy losses, arterial or venous thrombosis, and mild thrombocytopenia. Patients with APS require anticoagulation (eg, low-molecular-weight heparin in pregnant patients) to decrease the risk of complications.